1. Field of the Invention
The invention relates to a pointing device, and more particularly to a pointing device and method of enabling a pointing device to generate a control signal using magneto-electric conversion.
2. Description of the Related Art
FIGS. 1 and 2 illustrate a conventional pointing device that includes: an operator 18 supported on a base 17 and movable relative to a central axis (O′) of the base 17 in a direction (A) transverse to the central axis (O′); a magnet 11 carried on the operator 18 and disposed coaxially with the operator 18 in the base 17; a biasing member 12, such as a spring piece, disposed coaxially in the base 17 for biasing the operator 18 toward the central axis (O′); two magneto-electric transducers 13 opposite to each other in the direction (A) and disposed adjacent to the magnet 11; a differential amplifier 14 having inverting and non-inverting input ends coupled respectively to the magneto-electric transducers 13; a sampling unit 15 coupled to an output end of the differential amplifier; and a processing unit 16 coupled to the sampling unit 15.
Each magneto-electric transducer 13 detects magnetic field strength of the magnet 11 and generates an analog voltage signal based on a detection result made thereby.
The differential amplifier 14 receives the voltage signals from the magneto-electric transducers 13 and outputs a differential signal to the sampling unit 15.
The sampling unit 15 samples the differential signal from the differential amplifier 14 so as to generate a digital sampling voltage.
The processing unit 16 determines whether the sampling voltage from the sampling unit 15 is within a fixed voltage range corresponding to a reference displacement of the operator 18 from the central axis (O′). The processing unit 16 generates a control signal upon detecting that the sampling voltage is not within the voltage range, wherein the control signal is obtained by subtracting a center value in the voltage range from the sampling voltage. In this case, the control signal includes a polarity indicating an orientation of the magnet 11 (or the operator 18) relative to the central axis (O′), and a magnitude indicating a displacement of the magnet 11 (or the operator 18) from the central axis (O′).
However, since the biasing member 12 easily experiences elastic fatigue after a long period of use, the biasing member 12 cannot ensure the operator 18 to move back to an original position in the central axis (O′) such that misoperation of the conventional pointing device may be caused.
In order to avoid misoperation of the conventional pointing device, a larger reference displacement is required for the conventional pointing device to operate. The conventional pointing device therefore cannot ensure sensitivity in a relatively small operating area during use.